The Loch Ness Monster is a detailed evaluation of every photographically supported sighting of the loch's alleged denizen since 1933. Campbell offers the most plausible explanation of each, and concludes that none survives close inspection. While he lists the ancient mythology that has been retroactively postulated as evidence for Nessie's existence, he finds that it is nothing more than a desperate ploy to reinterpret older fairy tales as early sightings.
If Nessie exists, then its ancestor must have entered Loch Ness at some time in the past, when there was a tunnel from the loch to the open sea. But since Loch Ness is 16 meters above sea level, any tunnel large enough to take Nessie would drain the lake down to sea level. There is no tunnel, and probably never was a tunnel. And for the creature to have survived for centuries, there would have to be a breeding herd of at least twenty individuals. But Loch Ness is too cold to support any cold-blooded species, and also does not have the capacity to feed such a number of large lifeforms.
Campbell shows that all alleged positive results of sonar, radar and photographic imaging, on close inspection, in fact prove to be negative. Not only does the loch not have the capacity to support a herd of monsters. No legitimate evidence exists that it does contain them. And given the thousands of man-hours devoted to loch watching by serious searchers, photographers and tourists, the logical conclusion is that, if Nessie existed, someone would have proven it by now. But the more Loch Ness is watched, the less the alleged monster shows itself.
Campell concludes that there is absolutely no reason why anyone should believe in lake monsters. If anyone doubts that conclusion on the basis of any specific evidentiary claim, the chances are it is one of the dozens of claims that the book examines and demolishes.
Being an examination of the evidence (or lack thereof in the author's opinion) for the Loch Ness monster, while interesting, this book falls short on a few points. First off, it's extremely scientific tone makes for dry reading, yet on the other hand seems brief for it's intended purpose of thoroughness. Also, despite making some very good points the author tends to dismiss some evidence for reasons that would require more suspension of reality than would belief in a monster. In one case in particular, Mr. Campbell goes on for some pages discussing a case of evidence and abruptly dismisses it by stating that he came upon "rumors" of a hoax, the details of which he doesn't even go into. All in all, whether you are a believer or not, this book is interesting reading if you can get past the dry anylitical tone of it. However, be prepared to use the evidence presented to form your own opinion rather than buy into the author's emphatic belief that there simply cannot be a monster. Having visited the Loch in person myself, I find it very difficult to believe that someone could look into it's massive, murky depths and say with 100% certainty that there could not be something lurking below. But that is exactly what Mr. Campbell does with this book.